1. Field of the Invention
The invention relates to a coupling device for high pressure-tight threaded pipe connectors with a standard coupling body with a 24 degree connector, a coupling nut, to effect a pressure-tight connection and a standard pipe or a connection stub for connection to other system components.
2. Description of the Prior Art
With the customer threaded pipe connectors, the pipe when fitted is located in the proximity of the bore of the connector or of its inner bevel and is connected to the connector by a cutting ring or compression washer and a coupling nut.
Both during fitting and removal of the coupling, the pipe must be moved so far in an axial direction after releasing the coupling nut, that it can be removed radially. In those cases where the space required for fitting and removing the pipe in an axial direction is not available, the customer pipe couplings can therefore not be employed.
DE-Gbm 1 979 979 describes a threaded pipe connector in which, with the aid of a coupling nut and a compression washer, a pipe forms a butt joint, with a connector provided with a bore, whereby the bore is provided with an inner bevel, a cylinder face and an annular face arranged at right angles to the bore axis. In the bore of the connector a packing ring is arranged which can be clamped to the wall of the bore and which is provided with a radial stop face which when the threaded pipe coupling is fitted, abuts on to the annular stop face of a connecting compression washer.
A threaded pipe coupling of this type embodies certain characteristics which render it unsuitable for specific applications. The device incorporates several deformation points which make it difficult for the fitter to recognize correct seating by registering a sharp increase in the force required when tightening the device. The front face of the packing ring is provided with an annular edge and its outer circumferential face with an annular ridge. Both elements contribute to the clamping process so that both must be deformed during fitting. The adjacent compression washer and the pipe surface on which the compression washer acts are also subject to deformation. Due to the force required for this, which exceeds the tightening force of the packing ring, it is difficult or impossible for the fitter to recognize what stage the tightening process has reached. Furthermore, because of the deformation there are no clearly defined sealing surfaces which can withstand maximum pressures during fitting or refitting.
Finally, the prior device evidences ring shaped grooves and elevations on the inner surface of the flow channel which form resistance to the flow thereby causing eddy currents in the fluid which is unacceptable in certain applications.